The possibility and the advantage of using fluidized-bed electrodes in various electrochemical processes such as electrowinning of metals, or electrosynthesis of organic materials is increasingly recognized. The fluidized-bed electrode cells described in the literature present different configurations in regard to the geometry and location of anodes and cathodes, for example: side by side, concentric or plane parallel. Each of these configurations requires a minimum separation between the fluidized bed electrode and the auxiliary electrode to avoid short circuits between the oppositely charged electrodes. To achieve the separation, a porous membrane may be used as for example in the side by side and the concentric cells or by placing the auxiliary electrode at a sufficient distance above the fluidized-bed electrodes as in the plane parallel configuration. One major drawback found in these types of cells is the increased cell voltage created by either the distance between the auxiliary electrode and the main electrode or the diaphragm used to contain the fluidized-bed electrode and avoid short circuits.
The necessity for having the bed fluidized is governed by two factors: increasing the agitation so as to decrease appreciably the diffusion layer next to the electrode surface thus enabling high reaction rates, and avoiding agglomeration of the particles caused by welding through metal deposition in static parts of the bed. However, if the electrochemical reaction does not involve metal deposition but a partial reduction or oxidation of ionic species to different oxidation reduction states or, dissolution of metal composing the pariculated bed or, an organic electrochemical oxidation or reduction reaction at the surface of the particles resulting in gaseous or soluble products, the particles composing the bed need not be fluidized. The static bed could be comprised so as to be independent of the direction of flow of the electrolyte through the cell.